COS 234-5 - Energy balance analysis of crop and livestock production systems in the Loess Plateau, China

Background/Question/Methods

China's Loess Plateau is a 'museum' of a region using traditional ‘rain fed’, dryland agricultural systems. With the aim of further developing the integrated agricultural systems for improving on-farm energy use efficiency, and so achieve optimum productivity, arable and pastoral rangeland ‘monitor farms’ in this region were surveyed in 2017 and 2018, at three locations along north to south precipitation and temperature gradients (i.e. from low to high). Farm structure and farming practices were analyzed to estimate the energy balance of these two farm types. On the arable farms, a reduction in crop species richness and diversity, but increase in crop species evenness, correlated with the rising precipitation and temperature gradients from north to south.

Results/Conclusions

Over 80% of all energy inputs on these arable farms are related to their application of fertilizers: animal manure, urea, di-ammonium phosphate and NPK compound fertilizers; their energy input: output ratio being highest in the middle region, where it was twice that of the northern region, and 8 times that of the southern region (P< 0.05). All pastoral farms raise sheep, cattle, chickens and pigs, for which the inputs are mostly straw of cereal and legume crops, and corn grains. The energy input: output ratio of these pastoral farms correlates with the rising precipitation and temperature gradients from north to south, rising in the middle region to twice, and in the southern region to 3 times, that of the northern region (P< 0.05). Comprehensive analysis of the energy balances described above has led to the following adjustments to farm structure and management practice being made. In the northern region: increased herd and flock sizes to match pasture carrying capacity; fertilizer use matched with crop nutrient demand. In the middle region: crop area balanced with the animal manure produced from increased herd size. In the southern region: increased perennial legume and other annual forages’ acreage.